A man who found true love while setting up a Central Park art project has presented his girlfriend with a very special engagement ring – made from The Gates itself.

Mark Harder, 40, dropped on two knees earlier this month in a Massachusetts field and asked fellow Gates installer Amelia Hennighausen, 33, to marry him, offering up a small, metal nut, rather than a traditional diamond ring, as a symbol of their union.

The small piece, which once used to hold an orange upright to its base, now adorns Henninghausen’s finger.

“I think of it as the ring Mark asked me to be his wife with,” said Hennighausen, an associate photo editor from Williamsburg.

Harder, of Inwood, says he cut the ring to size himself and asked The Gates masterminds Jeanne-Claude and Christo for permission. “They think it’s wonderful that a small part of the project was recycled for love,” Harder, an audio engineer, said.

Jeanne-Claude told The Post: “One nut serving as an engagement ring is very touching and we love the idea.”

The couple have not set a date yet, but say Jeanne-Claude and Christo will be invited to the 2006 or 2007 affair.